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Method for improving permeability of oil sand reservoir by squeezing saturated CO2 brine

A permeability and CO2 technology, applied in earth-moving drilling, wellbore/well components, production fluid, etc., can solve the intensification of permeability heterogeneity, increase reservoir permeability, weaken permeability heterogeneity, etc. question

Active Publication Date: 2021-08-17
NORTHWEST UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a 2 The method of brine to improve the permeability of oil sand reservoirs solves the problem of intensified permeability heterogeneity along the wellbore direction in the existing oil sand squeeze technology, and achieves the expansion effect through CO without affecting the effect of traditional liquid squeeze. 2 The solution selectively dissolves the muddy components, and while increasing the overall permeability of the reservoir, it weakens the heterogeneity of permeability along the wellbore direction, thereby ensuring the uniform expansion of the steam chamber along the wellbore direction, increasing crude oil production, and improving crude oil production. recovery factor

Method used

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  • Method for improving permeability of oil sand reservoir by squeezing saturated CO2 brine
  • Method for improving permeability of oil sand reservoir by squeezing saturated CO2 brine
  • Method for improving permeability of oil sand reservoir by squeezing saturated CO2 brine

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Effect test

Embodiment 2

[0084] According to the present invention by squeezing saturated CO 2 Another embodiment of the method for improving the permeability of oil sand reservoirs with brine, its modification steps, working principle, beneficial effect, etc. are the same as those of Embodiment 1, the difference is the coefficient of variation of the permeability of the 12 layers: from top to bottom The coefficients of variation in permeability of the 12 layers are 0.35, 0.22, 0.35, 0.46, 0.34, 0.24, 0.58, 0.49, 0.38, 0.56, 0.77, and 0.43, respectively. The weight coefficients of the permeability variation coefficients of the 12 layers from top to bottom are 1 / 45, 2 / 45, 1 / 15, 4 / 45, 1 / 9, 1 / 9, 4 / 45, 1 / 15, 4 / 45, 1 / 9, 1 / 9, 4 / 45. The coefficient of variation of the overall permeability can be calculated to be 0.4502.

[0085] Because the overall permeability coefficient of variation is less than 0.5, conventional water injection is used for capacity expansion. In this example, wells I and P use conven...

Embodiment 3

[0087] According to the present invention by squeezing saturated CO 2 Another embodiment of the method for improving the permeability of oil sand reservoirs with brine, its modification steps, working principle, beneficial effect, etc. are the same as those of Embodiment 1, the difference is the coefficient of variation of the permeability of the 12 layers: from top to bottom The coefficients of variation in permeability of the 12 layers are 0.75, 0.82, 0.65, 0.86, 0.64, 0.84, 0.58, 0.79, 0.68, 0.86, 0.77, and 0.69, respectively. The weight coefficients of the permeability variation coefficients of the 12 layers from top to bottom are 1 / 45, 2 / 45, 1 / 15, 4 / 45, 1 / 9, 1 / 9, 4 / 45, 1 / 15, 4 / 45, 1 / 9, 1 / 9, 4 / 45. The coefficient of variation of the overall permeability can be calculated to be 0.7444.

[0088] Because the overall permeability coefficient of variation is greater than 0.7, CO injection at high temperature 2 Saturated saline expansion.

[0089] When the temperature incre...

Embodiment 4

[0092] According to the present invention by squeezing saturated CO 2 Another embodiment of the method for improving the permeability of oil sand reservoirs with brine, its modification steps, working principles, beneficial effects, etc. are the same as those of Embodiment 1, the difference is the matching relationship of various parameters in the modification steps:

[0093] This example is a SAGD well in Fengcheng Oilfield, Xinjiang. Well I has a vertical depth of 372m, well P has a vertical depth of 377m, and the fracture pressure gradient of the reservoir formation is 0.017MPa / m. Calculate the maximum wellhead pressure P for liquid extrusion construction max出口 = 2.2MPa. Wells I and P were squeezed in four stages: in the first stage, the wellhead pressures of the two wells were loaded from 0 to 0.55 MPa within 50 minutes, and the pressure of 0.55 MPa was maintained for 12 hours; in the second stage, the wellhead pressures of the two wells were from Load from 0.55MPa to 1....

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Abstract

The invention relates to a method for improving the permeability of an oil sand reservoir by squeezing saturated CO2 brine. The method comprises the following steps of calculating the overall permeability variable coefficient of a permeability profile, and reasonably selecting conventional water injection, injecting saturated CO2 brine at normal temperature and injecting CO2 saturated brine at high temperature; calculating a permeability improvement coefficient, and drawing a relationship between the initial permeability and the permeability improvement coefficient; reasonably controlling the pressure of the wellhead to gradually and slowly squeeze the saturated CO2 brine into the reservoir; recalculating the overall permeability variation coefficient, and when the overall variation coefficient of the stratum is reduced to be less than 0.5, determining that the transformation succeeds; and if the variable coefficient of the overall permeability of the stratum is still larger than 0.5, injecting CO2 saline water again at high temperature for 24 hours or prolonging the injection time by 2 days. On the premise of not influencing the traditional liquid extrusion expansion effect, the CO2 solution selectively corrodes argillaceous components, the permeability heterogeneity in the borehole direction is weakened while the overall permeability of a reservoir is increased, and therefore it is guaranteed that a steam cavity is evenly expanded in the borehole direction, the crude oil yield is increased, and the crude oil recovery rate is increased.

Description

technical field [0001] The invention belongs to the technical field of unconventional oil and gas reservoir transformation and oil and gas development, and specifically relates to a 2 A method for brine to improve permeability in oil sands reservoirs. Background technique [0002] The oil-squeezing oil-sand reservoir expansion technology was first applied to marine oil sands in the Alberta region of Canada. The sand-grain contact structure formed an "interlocking structure" similar to the state of over-consolidated soil under the action of glaciers. The continental heavy oil reservoir in Fengcheng Oilfield in Xinjiang has not experienced the compaction of glaciers, the reservoir structure is loose, and the physical interlayers are developed, and its expansion mechanism is different from that of Canadian marine oil sands. Heavy oil reservoirs in Fengcheng Oilfield mainly use Steam Assisted Gravity Drainage (SAGD) technology to exploit super heavy oil. Before preheating, hig...

Claims

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Application Information

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IPC IPC(8): E21B43/27
CPCE21B43/26Y02P90/70
Inventor 高彦芳任战利崔军平
Owner NORTHWEST UNIV
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